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<title>Berkeley DB Reference Guide: Replication environment priorities</title>
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<td><b><dl><dt>Berkeley DB Reference Guide:<dd>Berkeley DB Replication</dl></b></td>
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<p align=center><b>Replication environment priorities</b></p>
<p>Each database environment included in a replication group must have
a priority, which specifies a relative ordering among the different
environments in a replication group.  This ordering is a factor in
determining which environment will be selected as a new master in case
the existing master fails.  Both Replication Manager applications and
applications which use the Base replication API should specify
environment priorities.</p>
<p>Priorities are an unsigned integer, but do not need to be unique
throughout the replication group.  A priority of 0 means the system can
never become a master, regardless.  Otherwise, larger valued priorities
indicate a more desirable master.  For example, if a replication group
consists of three database environments, two of which are connected by
an OC3 and the third of which is connected by a T1, the third database
environment should be assigned a priority value which is lower than
either of the other two.</p>
<p>Desirability of the master is first determined by the client having
the most recent log records.  Ties in log records are broken with
the client priority.  If both sites have the same number of log
records and the same priority, one is selected at random.</p>
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